1. Field of the invention
The invention relates to a device for reading reliefs on a transparent container and, more particularly, to an optoelectronic device.
2. Description of the Related Art
Although it is not limited to such an application, the invention will be more particularly described with reference to the reading of the mould number inscribed on the bottom part of the body of a glass bottle. These numbers are usually produced in the form of codes comprising points obtained by hollows produced on the internal surface of the mould or else are produced in the form of a plain-language alphanumeric code.
The invention extends, of course, to any type of transparent container and to the reading of any type of relief, in the form of hollows or bumps, which is produced in the material of which the container is made or produced from added elements such as, for example, an enamel insert, etc.
In the bottle-manufacturing industry, it is usual to carry out checks for detecting defects and/or dimensional checks. When a manufacturing anomaly is detected, it is necessary to identify the production tool, that is to say the mould used for manufacturing the bottle that has the detected anomaly. Rapid identification of the mould is preferable, in order to remedy the production defect as quickly as possible.
This code is normally read by means of optical sensors positioned on the line conveying the bottles. When the bottles move onto the conveyor they arrive in random positions; to read the mould number consequently requires the bottle to be rotated about its vertical axis in front of the sensor so that the entire periphery of the bottle moves past the sensors. The sensors can thus reproduce the image of the mould number, which makes it possible to associate the manufacturing mould with the source of the bottle. Such a device combined with a device for checking the bottle makes it possible to identify the mould responsible for any anomalies on the bottle.
Such a reading technique is described especially in U.S. Pat. 4,816,668. Although such techniques effectively allow association of a manufacturing mould with anomalies detected on a bottle, they nevertheless have various drawbacks. These drawbacks are more particularly connected with the rotation of the bottles about their vertical axis in order to bring the mould number opposite the sensor, that is to say into a reading position. The drawbacks connected with this rotation are, first of all, wear of the bottle and of the tools which rub against the said bottle in order to rotate it. Problems also arise in adjusting these tools, more particularly in the case of a manufacturing change when the next bottle does not have the same dimensions.